From fac9e801f52e4655ce2c4d0c88f98a42a45d83f2 Mon Sep 17 00:00:00 2001
From: yusufcank34 <yusufcankilic369@gmail.com>
Date: Wed, 29 Oct 2025 18:29:16 +0300
Subject: [PATCH 1/4] Index: ensure Index(DatetimeIndex) returns DatetimeIndex
 (fixes #1440)

---
 pandas-stubs/core/indexes/base.pyi | 10 ++++++++++
 1 file changed, 10 insertions(+)

diff --git a/pandas-stubs/core/indexes/base.pyi b/pandas-stubs/core/indexes/base.pyi
index 25c975eff..ee98fe979 100644
--- a/pandas-stubs/core/indexes/base.pyi
+++ b/pandas-stubs/core/indexes/base.pyi
@@ -274,6 +274,16 @@ class Index(IndexOpsMixin[S1], ElementOpsMixin[S1]):
         name: Hashable = ...,
         tupleize_cols: bool = ...,
     ) -> IntervalIndex[Interval[Any]]: ...
+    @overload
+    def __new__(
+        cls,
+        data: DatetimeIndex,
+        *,
+        dtype: TimestampDtypeArg | None = ...,
+        copy: bool = ...,
+        name: Hashable = ...,
+        tupleize_cols: bool = ...,
+    ) -> DatetimeIndex: ...
     # generic overloads
     @overload
     def __new__(

From dbfe078db3c48fc45efefe20e9afd238aa54fc44 Mon Sep 17 00:00:00 2001
From: yusufcank34 <yusufcankilic369@gmail.com>
Date: Wed, 29 Oct 2025 20:58:56 +0300
Subject: [PATCH 2/4] Add isolated test for Index(DatetimeIndex) typing
 (GH#1440)

---
 tests/indexes/test_datetime_index_1440.py | 8 ++++++++
 1 file changed, 8 insertions(+)
 create mode 100644 tests/indexes/test_datetime_index_1440.py

diff --git a/tests/indexes/test_datetime_index_1440.py b/tests/indexes/test_datetime_index_1440.py
new file mode 100644
index 000000000..26d2d541c
--- /dev/null
+++ b/tests/indexes/test_datetime_index_1440.py
@@ -0,0 +1,8 @@
+from typing import assert_type
+import pandas as pd
+
+# GH#1440 – constructing Index from DatetimeIndex should return DatetimeIndex
+data = pd.date_range("2022-01-01", "2022-01-03", freq="D")
+idx = pd.Index(data, name="date")
+
+assert_type(idx, pd.DatetimeIndex)

From 773fdfc5fe7b8ce066997bdec17800e0e8fce049 Mon Sep 17 00:00:00 2001
From: yusufcank34 <yusufcankilic369@gmail.com>
Date: Wed, 29 Oct 2025 23:43:05 +0300
Subject: [PATCH 3/4] Fix: Index(DatetimeIndex) now returns DatetimeIndex;
 consolidated test (fixes #1440)

---
 pandas-stubs/core/indexes/base.pyi   | 4 +++-
 tests/indexes/test_datetime_index.py | 2 +-
 2 files changed, 4 insertions(+), 2 deletions(-)

diff --git a/pandas-stubs/core/indexes/base.pyi b/pandas-stubs/core/indexes/base.pyi
index ee98fe979..907e8c421 100644
--- a/pandas-stubs/core/indexes/base.pyi
+++ b/pandas-stubs/core/indexes/base.pyi
@@ -187,7 +187,9 @@ class Index(IndexOpsMixin[S1], ElementOpsMixin[S1]):
     @overload
     def __new__(
         cls,
-        data: Sequence[np.datetime64 | datetime] | IndexOpsMixin[datetime],
+        data: (
+            Sequence[np.datetime64 | datetime] | IndexOpsMixin[datetime] | DatetimeIndex
+        ),
         *,
         dtype: TimestampDtypeArg = ...,
         copy: bool = ...,
diff --git a/tests/indexes/test_datetime_index.py b/tests/indexes/test_datetime_index.py
index 221a12607..22d07e6b8 100644
--- a/tests/indexes/test_datetime_index.py
+++ b/tests/indexes/test_datetime_index.py
@@ -24,7 +24,7 @@ def test_index_relops() -> None:
     )
     x = pd.Timestamp("2022-01-17")
     idx = check(
-        assert_type(pd.Index(data, name="date"), "pd.Index[pd.Timestamp]"), pd.Index
+        assert_type(pd.Index(data, name="date"), pd.DatetimeIndex), pd.DatetimeIndex
     )
     check(assert_type(data[x <= idx], pd.DatetimeIndex), pd.DatetimeIndex)
     check(assert_type(data[x < idx], pd.DatetimeIndex), pd.DatetimeIndex)

From c5b0d15370dab9e97b9a35e80167f1d8cf8d41bc Mon Sep 17 00:00:00 2001
From: yusufcank34 <yusufcankilic369@gmail.com>
Date: Thu, 30 Oct 2025 21:49:38 +0300
Subject: [PATCH 4/4] Remove redundant test_datetime_index_1440.py and run
 pre-commit

---
 tests/indexes/test_datetime_index_1440.py | 8 --------
 1 file changed, 8 deletions(-)
 delete mode 100644 tests/indexes/test_datetime_index_1440.py

diff --git a/tests/indexes/test_datetime_index_1440.py b/tests/indexes/test_datetime_index_1440.py
deleted file mode 100644
index 26d2d541c..000000000
--- a/tests/indexes/test_datetime_index_1440.py
+++ /dev/null
@@ -1,8 +0,0 @@
-from typing import assert_type
-import pandas as pd
-
-# GH#1440 – constructing Index from DatetimeIndex should return DatetimeIndex
-data = pd.date_range("2022-01-01", "2022-01-03", freq="D")
-idx = pd.Index(data, name="date")
-
-assert_type(idx, pd.DatetimeIndex)